The amount of pure shit something is composed of, this can be real or metaphorical shit. The largest coefficient every recorded was .89 by a Tuna but that record has recently been broken and is now 1.5, proving everything we thought we knew about percentages to be a lie.

"Yo mang, that gurl ain't nearly as cool as we thought she was"
"Yeah, her coefficient of shit must be around a .9"